Width recorder for traveling webs



i 6, 1954 J. E. GARRETT ET AL 2,674,151

WIDTH RECORDER FOR TRAVELING WEBS Filed May 20, 1952 ECORDEQ INVENTORS J'OH/V E. GARRETT Ii 9. Z M c/ AEL a. MmeL/Tz mom a ATTORNEYS Patented Apr. 6, 1954 UNITED STATES PATENT OFFICE WIDTH RECORDER FOR TRAVELING WEBS John E; Garrett, New Haven, and Michael B.

Karelitz, Fairfield, Conn., assignors'to Olin Industries, Inc., a corporation of Delaware Application May 20, 1952, Serial No. 288,981

5 Claims. 1

This invention relates to means for recording the width of a traveling web or'similar continuous strip or film, and in particular is directed to an improved means forcontinuously recording the width of a cellophane film as the film is wound up at the dry end of a castingmaohine'.

In the manufacture of cellophane film and the like, the film is commonly cast in a continuous length that is trained'suocessively through the various film processing treatment and through drying means, and then'fina-lly wound up at the dry end of the casting machine in the form of a mill roll of relatively great width and diameter. Normally, the cellophane film thus formed is subsequently taken from these mill rolls andrun through slitting machines in order to form smaller rolls in accordance with the dimensional specifications for ultimate use of the film;

An important problemin thiscourse of manufacture of the cellophane is the proper cor relation of the casting operation with the subsequent slitting procedures to avoid width varia tions in the castfilm insofar'as possible so that a minimum of edge trim 'wasteresu'lts in the slitting operation, and further "to know ofthe'width variations that have occurred 'so as to'adjust the slitting operation for obtainingthe best possible advantage of the cast film. It has p v s y been proposed to solve this problem by providing a width indicating system on the casting machines from which a continuous record "could be obtained of the width of a cellophane film being cast. However, the operation of 'such' systemshas been complicated by the fact that as a cellophane film is being formed on a casting machine it may not only vary in width but may sway from side to side, and the effect of this sway on the indicating system must be eliminated if a true indication of width is to be obtained.

In accordance withthe present invention, a width recording means is provided that is uniquely arranged to obviate any effect of him sway on the width recording indication obtained. This is done according to the present invention by arranging separate laterally adjustabl electronic scanning means adjacent each side edge of the cellophane film for detecting the film edges as the film is being wound up at the dry end of the casting machine and providing associated servo means'for laterally adjusting each scanning means upon deviation of the detected film edges and thereby maintaining these scanning means in continuous tracking relation with" the respective side edges ofthe film; In this manner the spaced scanning meansarecausea' to-maintain continuously a spacing that indicates precisely the true film width irrespective of 'any film sway, and from which a true indication of the film width may be continuously recorded as a constant check on the operation of the casting machine and for subsequent reference in handling themill rolls through the slitting machines.

The width recording means of the present invention is described in further detail below in connection with the accompanying drawings, in which:

Fig. 1 i a'plan view illustrating'in more or less diagrammatic form' an arrangement for a width recorder embodying the present invention; and

Fig. 2 is a transverse section taken substantially on the line 2-2 in Fig. 1.

Referring now in detail to the drawings, and more particularly at first to Fig. l, the reference numeral Ill indicates the separate electronic scanning means arranged-in accordance with the present invention for tracking the respective side edges of a continuous cast cellophane film F or the like as the film'is traveling at the dry end of a casting machine to be wound into a mill roll.

Each scanning means l0 is provided with an input connection as at I0 which ma be from a standard V. A. C. line, and preferably takes the form of a photoelectric unit comprising, in the conventional manner, alight source, an appropriate optical train, and a phototube (not shown), such as is embodied in the rotary lens scanning head (CR-7515-P20l-G1) manufacture by the General Electric Company. Effective detection of the edges of film F by these units [0 is advantageously provided for by disposing a film guide roll l2 on the casting machine below the units [0 (compare Fig. 2) and equipping this roll 12 with a surface, suitably a dull black surface, having different reflection properties from thefi'lm F so that the phototubes of the units it may be operated by this differential reflection to signal any deviation of the film edges.

The output from these phototubes of the units I0 i connected through'circuit means as indi cated at M to control means represented at it from which operating circuits as at [8 run to driving means .26 that arein turn coupled at 22 for effecting lateral adjustment'of the scanning units Ill and thereby complete a closed cycle servome'chanism at each side edge of the film F. The control means It also has an input connection as at I6 suitably'running from a standard 110 v. A. 0; line, and" is employed to receive any film' edge deviation signal transmitted from the phototube units I and thereupon actuate a compensating servo response through operation of the driving means 20. For this purpose, the control means I B suitably comprises an electronic circuit arranged to detect the direction of a signaled film edge deviation, amplify the signal, and apply the amplified signal to the proper one of two grid controlled rectifiers, all of which are well known elements of electronic control means that are readily available, as in the Thyratron control for variable speed D. C. motor (CR-7515- S203-G1) manufactured by the General Electric Company. The driving means may then consist of a reversible direct current motor (such as the 1/40 H. P. General Electric Model BC26- AC204) operated by the rectified output from the control means [6 in the direction indicated by the film edge deviation signal to adjust the involved scanning means l0 laterally until the deviation signal is no longer transmitted.

Provision for the lateral adjustment of the scanning means In may be made conveniently (as shown in Fig. 2) by fitting them with racks 24 arranged to rest on supporting pinions 26, with one of the pinions 26 connected as by a shaft 28 to the coupling means 22, that may take the form of a suitable gear train (not shown), for driving in response to the operation of the motor 20. In

this way a continuous lateral adjustment of the scanning means I0 is obtained to maintain them in constant tracking relation at the side edges of the film F, and accordingly, it is only necessary in addition to provide means for indicating the spaced location of the two scanning means ill at any given time in order to obtain a width record of the film F at that time.

The recording operation is accomplished according to the present invention by arranging variable impedance means 30, such as helical po tentiometers of the type disclosed in U. S. Patent No. 2,473,048 (i. e., 10 turn Helipots or Gibbs Micropots), for actuation from each servomotor coupling means 22 so that they will be varied in correspondence with lateral adjustments of the scanning means In for film edge deviation. For this purpose we have found that the coupling means 22 may advantageously consist of a gear box arranged with an output of 180:1 for lateral adjustment of the scanning means I0 and a second output of 6:1 for actuation of the potentiometers 30.

For standard film width with the film on center in the casting machine, the arrangement of the potentiometers 30 is such that they are set at midpoint. Accordingly, if the film width increases or decreases, the resistance of the potentiometers 30 will be varied in correspondence as the servo operation restores the scanning means ill. on the other hand, the effect of film sway would be merely to decrease the resistance of one potentiometer 30 by the same amount that the resistance of the other one increased, assuming that no variation in film width took place. Consequently, by connecting the potentiometers 3!] in series as indicated at 32, the total resistance will be at all times directly proportioned to the film width and unaffected by swaying of the film F on the casting machine.

The resistance indicated by the series connected potentiometers 30 may be recorded by connecting a suitable measuring instrument as at 34 across the series circuit 32. This measuring instrument 34 is advantageously an impedance bridge type recording device, such as is disclosed in U. S. Patent No. 2,162,469 (1. e., Bristol Dynamaster) which makes it unnecessary to have a highly regulated direct current power supply to energize the potentiometers 30 or a standard cell and batteries for the recorder. The recording device 34 may be provided with a standard v. A. C. line connection at 34', and may be readily calibrated directly in inches deviation of film width from standard and arranged to provide a continuous record of film width variation correlated with each mill roll cast.

The present invention has been described above for purposes of illustration only and is not intended to be limited by this description or otherwise except as defined in the appended claims.

We claim:

1. A width recorder for a traveling web comprising a guide roll for said web provided with a surface having different reflective properties from said web, laterally adjustable photo-tube scanning means mounted above said guide roll and adjacent each side edge of said web for detesting the lateral position of said edges, by the diiferential reflection from the surface of said guide roll and said web, said phototube scanning 3 means being operated from said differential refiection to signal electrically any lateral deviation of said edges, servo control means connected to each of said phototube scanning means for controlling lateral adjustment thereof, said servo control means each being actuated electrically in response to edge deviation signals from the respective phototube scanning means and being mechanically connected respectively to said phototube scanning means for effecting compensating lateral adjustment thereof in response to said deviation signals thereby to maintain each of said phototube scanning means independently in continuous tracking relation with said detected web edges, and means responsive to the respective laterally adjusted positions of said phototube scanning means for continuously indicating the lateral spaced relation of said phototube scanning means as a measure of said web width.

2. Means for continuously recording the width of a cellophane film or the like as the film is traveling on a casting machine, said means comprising a film guide roll disposed on said casting machine and provided with a surface having different reflective properties from said film, phototube scanning means mounted for lateral adjustment on said casting machine above said guide roll and adjacent each side edge of said film to detect the lateral position of said edges by the differential reflection from the surface of said guide roll and said film, said phototube scanning means being operated from said difierential reflection to signal electrically any lateral deviation of said edges, servo control means connected to each of said phototube scanning means for controlling lateral adjustment thereof, said servo control means each being actuated electrically in response to film edge deviation signals from the respective phototube scanning means and being mechanically connected respectively to said phototube scanning means for effecting compensating lateral adjustment thereof in response to said deviation signals thereby to maintain each of said phototube scanning means independently in continuous tracking relation with acid detected film edges, and means responsive to the respective laterally adjusted positions of said phototube scanning means for continuously indicating the lateral spaced relation of said phototube scanning means as a measure of said film width.

3. Means for continuously recording the width of a cellophane film or the like as the film is traveling on a casting machine, said means comprising a film guide roll disposed on said casting machine and provided with a surface having difierent reflective properties from said film, separate photoelectric units mounted for lateral adjustment on said casting machine above said guide roll and adjacent each side edge of said film to detect the lateral position of said edges by the dillerential reflection from the surface of said guide roll and said film, said photoelectric units being operated from said differential reflection to signal electrically any lateral deviation of said edges, servo control means connected to each of said photoelectric units for controlling lateral adjustment thereof, said servo control means each being actuated electrically in response to film edge deviation signals from the respective photoelectric units and being mechanically connected respectively to said photoelectric units for effecting compensating lateral adjustment thereof in response to said deviation signals thereby to maintain each of said photoelectric units independently in continuous tracking relation with said detected film edges, and means responsive to the respective laterally adjusted positions of said photoelectric units for continuously indicating the lateral spaced relation of said photoelectric units as a measure of said film width.

4. Means for continuously recording the width of a cellophane film or the like as the film is traveling on a casting machine, said means comprising a film guide roll disposed on said casting machine and provided with a surface having different reflective properties from said film, separate photoelectric units disposed for lateral adjustment on said casting machine above said guide roll and adjacent each side edge of said film to detect the lateral position of said edges, said photoelectric units being operated from said difierential reflection to signal electrically any lateral deviation of said edges, separate electrical motor control means electrically connected with each of said photoelectric units and actuated in response to film edge deviation signals from the respective photoelectric units, separate reversible electric motors mechanically connected with each of said photoelectric units for lateral adjusting movement thereof, said motors being operated by said control means in response to said deviation signals to effect compensating lateral adjustment 5 of said photoelectric units and thereby maintain said units in continuous tracking relation with sad film edges, and means responsive to the respective laterally adjusted positions of said photoelectric units for continuously indicating the lateral spaced relation of said photoelectric units as a measure of said film Width.

5. Means for continuously recording the width of a cellophane film or the like as the film is traveling on a casting machine, said means comprising a film guide roll disposed on said casting machine and provided with a surface having different reflective properties from said film, separate phototube scanning means disposed for lateral adjustment on said casting machine above said guide roll and adjacent each side edge of said film to detect the lateral position of said edges, said phototube scanning means being operated from said differential reflection to signal electrically any lateral deviation of said edges, servo control means connected to each of said phototube scanning means for controlling lateral adjustment thereof, said servo control means each being actuated electrically in response to film edge deviation signals from the respective phototube scanning means and being mechanically connected respectively to said phototube scanning means for effecting compensating lateral adjustment thereof in response to said deviation signals thereby to maintain said phototube scanning means independently in continuous tracking relation with said detected edges, separate potentiometers electrically connected in series and mechanically coupled with each of said servo control means for respective variation in correspondence with the compensating lateral adjustments of said phototube scanning means, and an electrical recording device connected across the series connection of said potentiometers for continuously recording the total effect of said potentiometers to indicate the lateral spaced relation of said phototube scanning means as a measure of said film width.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,514,985 Banner July 11, 1950 2,548,590 Cook Apr. 10, 1951 

